Tunneling machine with shield supported traveling excavator



J. R. TABOR Oct. s, 1968 TUNNELING MACHINE WITH SHIELD SUPPORTEDTRAVELING EXCAVATOR Filed July 13, 196e 6 Sheets-Sheet l lauern-ola JOHNE'. THBGQ m, J-Lu AT TQQNEYS Oct. 8, 1968 J. R. TABOR- 3,404,920

TUNNELING MACHINE WITH SHIELD SUPYPOR'ID TRAVELING EXCAVATOR Filed July1s, 196e e sheets-sheet' m u :N1-an Jol-IN E.' 'maalt J. R. TABOR O'ct.8, 1968 TUNNELING MACHINE WITH SHIELD SUPPORTED TRAVELING EXCAVATOR 6Sheets-Sheet 3 Filed July l5, 1966 NEN-ron Jaw/v E maak l MIMM ATTORNYJ. R. TABOR 3,404,920

TUNNELING MACHINE WITH SHIELD S-UPPORTED TRVELNG EXCAVATOR Oct. 8, 19686 Sheets-Sheet 4 Filed July 13, 1966 AT1-aannam Oct. 8, 1968 J. R. TABOR3,404,920

TUNNELING MACHINE WITH SHIELD SUPPORTED TRAVELING EXCAVATOR Filed July13, 1966 6 Sheets-Sheet 5 ATTO RHI-YS J. R. TABOR y' Oct. 8, 1968TUNNELING MACHINE WITH SHIELD SUPPORTED TRAVELING EXCAVATOR Filed July15, 196e 6 Sheets-Sheet 6 A INUENToE ../QHN E. Tqaoe ATTO RNEYS QQ am MM,um IMM-L i' United States Patent O 3,404,920 TUNNELING MACHINE WITHSHIELD SUP- PORTED TRAVELING EXCAVATGR John R. Tabor, 3400 Spruce St.,Racine, Wis. 53403 Filed .Iuly 13, 1966, Ser. No. 564,844 18 Claims.(Cl. 299-31) ABSTRACT OF THE DISCLOSURE This disclosure relates to atunneling machine comprising a tunneling shield, an excavator supportmechanism on the shield and conveyed by the shield as it moves forwardlyin the tunnel, a power operated excavator mounted on the supportmechanism to be carried within the shield and conveyed by the shield,said excavator having a boom, a cutting tool and means for moving thecutting tool in all directions across the tunnel face.

This invention relates to a tunneling machine.

The tunneling machine of the present invention consists of a poweroperated excavator supported in elevated relation to the tunnel floor onthe sides of a tunneling shield modified to bear tracks on its sides tosupport the excavator for movement with respect to the tunnel face. Themachine of the present invention is particularly designed to tunnelthrough hard ground and ssured or broken rock.

An important feature of the tunneling machine of the present inventionis the articulate mounting of the cutting tool by`which it may be swunguniversally in all directions to cut the spoil from the face of thetunnel. Desirably, the cutting tool incorporates a bucket by which thespoil may be transported between the tunnel face and take out apparatus,such as mine boxes, carts, a belt conveyor or other conveyanceapparatus.

By mounting the excavator on the shield, it will be conveyed forwardlyin the tunnel automatically when the shield is moved forwardly and bythe same apparatus which is used to periodically advance the shield.Moreover, the shield furnishes elevated support for the excavator. Inthis manner the utility of the shield is greatly enhanced. The shieldbecomes an integral part of the tunneling machine, while continuing toperform its conventional functions.

In the disclosed embodiment of the invention, the shield is providedwith longitudinal tracks along its sides and about midway between itsroof and iioor. The excavator consists of a central rigid tubular frameor backbone having Outrigger arms or beams with end carriages which rideon the shield tracks. Mechanism is provided to advance and retract theexcavator on said tracks to and from the face of the tunnel, whereby tofacilitate transfer of cut debris from the face to the take outapparatus.

The excavator of the present invention is power operated. It is adaptedto be made in dilferent sizes to operate in tunnels of various sizes.The excavator must cut and remove large amounts of heavy material. Forthis service, the machine has a heavy demand for power. The motors fortunneling machines embodying the invention, and adapted to work intunnels from 12 to 24 feet in diameter, typically have an aggregatepower requirement in the range of 350 yH.P. Accordingly, all of themechanismv must be strong enough to transmit this much power. In apractical embodiment of the invention, the 'excavator weighs about 50tons. Notwithstanding the high weight,

strength and capacity of this device, its power transmission mechanismis concentrated into a relatively compact assembly within the tubularframe aforesaid. This frame is desirably disposed substantially at thecentral axis of ice the tunnel. Accordingly, there is ample clearancebeneath the excavator for the take out apparatus and ample space aboutthe central tubular frame for Workmen. This structure alsoadvantageously locates the boom and the cutting tool for easily reachingall areas of the tunnel face.

In preferred embodiments of the invention, the various working motors,such as rams, jacks and rotary motors, are hydraulically operated.Pressurized hydraulic fluid for these motors is provided by one or morehydraulic pumps actuated by one or more electric motors. This provides aconvenient, simple and easily controlled power transmission forenergizing the various parts of the mechanism. The electric motors areenergized by a power cable extending to an energy source remote from thetunnel.

An advantageous feature of the hydraulically operated embodimentsresides in the ducting of the hydraulic lines within the Wall or bodyparts of the pistons, cylinders, etc., thus to eliminate as much aspossible exposed hydraulic hoses and protect the lines from breakagehazards.

Other objects, features and advantages of the invention will appear fromthe following disclosure in which:

FIG. 1 is a View partially in vertical axial section and partially inside elevation of a tunnel showing a tunneling machine embodying thepresent invention in position for use.

FIG. 2 is another view of the apparatus of FIG. 1, par tially inhorizontal axial section and partially in plan. Various positions of thecutting tool, its support boom and its rotatable head are illustrated inthis figure.

FIG. 3 is a lateral cross section taken along the line 3 3 of FIG. 1.

FIG. 4 is an enlarged fragmentary horizontal cross section, as along theline 4 4 of FIG. 3.

FIG. 5 is a cross section taken through one of the chain housings of theboom, substantially along the line 5 5 of FIG. 1.

FIG. 6 is a cross section taken along the line 6 6 of FIG. 4.

FIG. 7 is a cross section taken along the line 7 7 of FIG. 4.

FIG. 8 is a cross section taken along the line 8 8 of FIG. 4.

FIG. 9 is a detailed view, partly in cross section and partly inelevation, showing the power transmission arrangement of hydraulicmotors, gear reducers and feed pinions by which the head sleeve or neckwithin the frame tube is rotated.

FIG. 10 is a fragmentary, greatly enlarged view similar to FIG. 8.

FIG. 11 is an enlarged cross section taken along the line 11 11 of FIG.7, showing details of the gear reduction mechanism between the hydraulicmotors for the rotating head sleeve and the drive pinions therefor.

FIG. 12 is a perspective view of one of the end carriages on which theexcavator is supported from a track `on the tunneling shield.

FIG. 13 is a fragmentary vertical cross section taken :along the line 1313 of FIG. 4.

FIG. 14 is an enlarged perspective view of one of the wheels in thecarriage and the fluid actuated piston on which it is mounted.

FIG. 15 is an enlarged cross section taken through the carriage andshowing the pressure system for maintaining pressure on the carriagewheels.

FIG. 16 is an enlarged cross section taken through the hydraulic motoror ram which swings the boom.

FIG. 17 is a fragmentary cross section taken along the line 17-17 ofFIG. 16.

FIG. 18 is an enlarged cross section taken through one of the hydraulicmotors in the chain case of FIG. 5.

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention which may be embodied inother specific structure. The scope of the invention is defined in theclaims hereto.

As shown in FIG. 1, excavation of the tunnel is facilitated by aconventional shield which is periodically shoved forwardly toward thetunnel face 19 by hydraulic motor rams 21. As the shield 20 is movedforwardly through the tunnel, the excavated part of the tunnel behindthe shield is supported by curved ribs or beams 22 and wooden or steellagging or plates 23. This is conventional in the tunneling art. Therams 21 react against the most recently emplaced rib 22 in thrusting theshield 20 forwardly. The excavated spoil or earth debris is movedrearwardly through the shield on mine cars 0r other means of conveyance.

The tunneling machine of the present invention comprises an excavator 18mounted on channel-shaped tracks 24 which face inwardly toward thecenter axis of the shield and which are mounted on brackets 25 to ribs26 within the shield 20. The excavator 18 is novel in construction andcomprises a tubular frame 27 which functions as a rigid backbone or bodyfor the excavator.

Tracks 24 are desirably further supported near their rear ends by struts29 which are disposed obliquely as shown in FIG. 1. The ends of struts29 remote from tracks 24 are supported on brackets 30 attached to theribs 26 near their foot ends. Tracks 24 are desirably disposed somewhatabove the center axis of the tunnel shield, to clear as much workingspace therebelow as possible.

Tubular frame 27 is elevated above the shield floor by Outrigger beamsor arms 28 which extend laterally toward the tracks 24. Arms 28 havecoupling plates 31 removably attached by bolts 32 or the like tocomplementary plates 33 on stub beams or arms 34 which carry at theirends carriages 35 from which project a plurality of wheels 36 inpressure contact with the side iianges 37 and connecting web 38 of thetrack 24. See FIG. 13.

Each wheel 36 is mounted `for rotation on its motor piston 42. Therespective motor pistons 42 are movable in respective cylinders 43within the carriage 35. The several cylinders 43 are connected by ducts44 with a hydraulic fluid chamber 45 having a free piston 46 subject tothe pressure of nitrogen gas or the -like in piston cylinder chamber 47.The nitrogen gas is under pressure of about 2000 p.s.i. The gas isfurnished under pressure through valve 49. Accordingly, the respectivewheels 36 are biased under considerable pressure against the channeltrack 24 to take up any slack between the track walls and the carriage.

Within its tubular backbone 27, the excavator 18 is provided with arotatable sleeve 48 journaled for rotation on the anti-friction bearings50, 51. Front end bearing 50 is supported on annular ring 39 whichaligns laterally with the forward set of Outrigger beams 28, to receivedirect bracing support therefrom. Rear end bearing 51 receives supportfrom tail block 99 mounted within the tube 27 on support ring 100 whichaligns with the rearward set of Outrigger beams 28 to receive directsupport therefrom.

' The end of sleeve 48 projecting frontally beyond front bearing 50 isprovided with a rotary head 53. Two sets of paired ears 54 projectforwardly from the head 53 and at one side of the -axis of headrotation. An excavator boom 55 is pivotally connected on the ears 54 bypins 56. The boom has two housing portions 57, 58 which respectivelycontain bucket drive chains 61, as shown in FIG. 5. At the end of theboom 55 is mounted a bucket 62 which has earth cutting teeth 63. Thebucket and teeth are typical of a cutting tool with which the boom canbe provided. The toothed bucket will not only cut into the tunnel face19 to remove earth and debris therefrom,

but will convey rearwardly the cut material in the bucket as willhereinafter be described.

Bucket 62 is rotatable on bearing 64, as shown in FIGS. 2 and 4, in thedirection of arrows 65, through about 340. The bucket 62 has a shaft 66which extends rear wardly from the bucket into bracket 67 by which thebucket is mounted on the boom 55, and which also provides an internalcylindrical chamber 68 for a hydraulic motor. See FIG. 6. The bucketshaft 66 has a vane 71 projecting across the chamber 68. The chamber hasa fixed vane or partition 72 to either side of which hydraulic uid maybe admitted through the hydraulic lines 73, 74 through the ducts 75, 76.

Body bracket 67 is mountedto the boom 55 on transverse stub pintles 77,79 which project into the boom chain housings 57, 58, and which turn inthe direction of arrows 78 in FIG. 2, through about 180. The pintles 77,79 are rotated by respective sets of hydraulic motors 81, 82 in thechain cases 57, 58, as shown in FIG. 5. The pistons of the motors 81, 82are connected to the chains 61 which respectively are connected to thecoupling rings 83 respectively fastened to the pintles 77, 79. The chainlinks are fastened to end pins 84 in ears 85 projecting -laterally fromthe rings 83.

There is chain 61 in each housing 57, 58 with corresponding hydrauliccylinders 81, 82. Hydraulic uid under pressure is communicated to thecylinders 81, 82 through piping 97.

The boom 55 may be swung about the axis of its support pintles 56 by thehydraulic motor ram 86 which is connected to the boom 55 on pin 87, andby pin 89 to ears 88 which extend laterally from head 53. Jack 86 isprovided with hydraulic fluid through piping 90, 93, 97. Accordingly,the boom 55 may be rotated about the pins 56 as indicated by the arrows92 in FIG. 2, through about 120.

The rotatable sleeve 48 in the fixed tube 27 is rotated by a pluralityof hydraulic rotary motors 94, shown in FIGS. 7 through 11. In apractical embodiment of the invention, there are some fifty-two of thesemotors 94 clustered about a central tube which is fast to the stationarytail block 99, and thence to tube 27 through ring 100, and is shoulderedat 91 to bear on rotary sleeve 48. Stationary tube 95 has a hollowinterior 96 which provides a conduit for the hydraulic lines 97, 98,etc.

The central, fixed tube 95 is coaxial with and is radially spaced fromrotatable Sleeve 48 so that there is an annular space or chamber 103therebetween. The motors 94 and the associated transmission mechanismare mounted in said annular space 103.

In the disclosed embodiment, fixed central tube 95 is provided with twoaxially spaced annular channels 102 respectively having axially spacedflanges 104 which have sleeve bearings 101 (FIG. 9) for the respectiveshafts 106 of an annular series of toothed pinions 107. Each annularseries of pinions 107 mesh as with a ring gear 108 which is fast bylocking keys 109 to inside of sleeve 48.

There are speed reducing gear transmission sets 112 between each motor94 and its driven pinion 107, as best shown in FIGS. 9 and 11. Thedetails of each transmission gear set 112 is broadly immaterial, thestructure herein shown being for exemplication only. Each hydraulicmotor 94 has a shaft 113 and pinion 114 fixed thereon. Pinion 114 mesheswith a series of arcuately disposed pinions 115, each having a shaft 116mounted on a cage having an axially extending gear 118. Each pinion alsomeshes with the teeth on a ring gear 117 on the inside of housing 112.Pinions 115 walk around the ring gear 117 and rotate the cage 110, thusto turn its gear 118.

There is a second cage 125 with a set of pinions 119 which walk aroundthe inside of another ring gear 120 on the inside of housing 112, aspinions 119 are turned on their shafts 123 by gear 118. Cage 125 has anoutput shaft 106 keyed to a drive pinion 107. Accordingly, the

hydraulic motors 94 can be driven at relatively high speed, the speedbeing greatly reduced at the output pinions 107. As isshown in FIG. 4,there may be several circular rows of motors 94 clustered about thecentral, fixed tube 95, four rows being shown in FIG. 4. The motors 94and transmission 112 are staggered at opposite sides of the channels102. Accordingly, power is transmitted from the hydraulic motors 94smoothly to many points of power transmitting thrust contact with thesleeve 48.1

Hydraulic uid for pressurizing the various hydraulic motors derives fromone or more pumps 126 driven by one or more electric motors 127. Pumpoutput goes through a control valve console 128 by which the uid isdirected and controlled for each of the hydraulic motors above referredto, as through lines 97, 98, etc.

- As shown in FIGS. l and 3, the excavator is elevated from floor 131 ofthe tunnel. This places it substantially on the center axis of thetunnel so that the toothed bucket 62 can most conveniently reach allparts of the tunnel face 19. Tunnel oor 131 may be provided with tracks132 for mine cars 133 by which earth and other debris removed from thetunnel face 19 can be taken out of the tunnel and disposed of.Alternatively, a conveyor belt or the like may function as take outapparatus as a substitute for the tracks 132 and mine cars 133. In anyevent, the tubular frame 27 of the machine is desirably elevated clearof the floor and is disposed in compact array near the axis of thetunnel so as to leave room therebeneath for the mine cars or the beltconveyor, and toprovide ample room about the machine for movement ofoperation personnel.

The excavator 18 may be advanced and retracted longitudinally of thetunnel on the channel tracks 24. This movement is also desirably poweredhydraulically. For this purpose, hydraulic rams 134 are provided at eachside of the machine. For each ram 134 there is a bracket 136 attached tothe tail end of corresponding track 24. Bracketv136 has a coupling 138,such as a ball joint, to the end of piston rod 139 of the jack 134. Eachjack 134 desirably has a piston 142 movable in jack cylinder 143.Cylinder 143 has hydraulic fluid at both sides of piston 142, undercontrol of the valve console 128. Cylinders 143 are attached to theexcavator arms 34 bybrackets 145.

Accordingly, the excavator 18 maybe moved longitudinally of the shield.In a practical embodiment, the range of movement is twelve feet and sixinches.

In operation, the excavator bucket 36 is'manipulated by an operator atconsole 128 to excavate the tunnel face. The boom 55 can swing laterallyabout pivot pins 54. The boom may also rotate about the axis of rotationof the sleeve 48. The bucket 62 is not only rotatable on its ringbearing 64, but can be swung about the` axis of pintles 77. Accordingly,the cutting tool is subject to universal movement for good control ofexcavating motions thereof. A full bucket can be retracted by thehydraulic motors 134 to deposit the bucket load in a mine car 133 or ona conveyor belt or the like. Advance of the shield under pressure ofhydraulic jacks 21 concurrently advances the excavator 18.

The excavator 18 could be supported on mechanism other than the tracks24, for example, on a conventional jumbo or on tracks laid on the tunneloor. However, the disclosed embodiment in which the excavator is mountedfrom tracks on theV side of the shield 20 has the advantagesaforest'ated which make the disclosed embodiment greatly preferred.

FIG. 16 shows details of the double-acting multi-stage hydraulic motoror ramY 86 for actuating the excavator boom 55. This figure illustratesan important feature of the invention in which the hydraulic lines fromthe pump 126 are protected from injury by ducting the lines within thewalls of the hydraulic motor parts, such as the cylinder, piston, etc.

Motor 86 comprises a base cylinder 150 which is pivotally mounted on thesupport ears 88 on pintles 89. Within cylinder 150 is an annular piston153 which supports one end of a sleeve cylinder 151 which is slidable inring bearing 160 at the end of cylinder 150. Within the sleeve 151 thereis another piston 154 which supports one end of piston rod 152 which isslidable in ring bearing 161 at the end of sleeve cylinder 151. The endof rod 152 carries the pintle 87 which is connected to suitable bearingson the boom 55.

Hydraulic fluid is supplied from pumps 126 to the chamber l155 withincylinder 150 through the fluid line 93 through a rotary bearing 156 inpintle 89, and through ducts 157, 158, 159 formed in the wall of thecylinder 150. Pressure within chamber 155 is exerted on both the annularpiston 153 for sleeve cylinder 151 and on the piston 154 for the rod152, whereby to extend the ram 86 and swing boom 55.

Means are provided for retraction of the motor 86 in two stages and atselected different speeds. For one stage hydraulic fluid is furnishedfrom pipe through the rotary bearing 162 in the other pintle 89 :andthrough the ducts 163 and 164 to an annular space or chamber 165 betweencylinders and 151. Pressure in chamber 165 will move the sleeve cylinder151 to the left in FIG. 16. Fluid trapped in chamber will be exhaustedthrough line 93.

For another stage of motor retraction fluid pressure is derived throughline 97 which is coupled to the pintle 87 on the rotatable coupling 166and through the internal ducts 167, 168, 169 into a chamber 172 formedbetween the piston rod 152 and the sleeve cylinder 151. Pressure inchamber 172 will be exerted on piston 154 to move the rod 152 to theleft in FIG. 16 for additional retractive movement of the motor 86. Ifthe pipes 90, 97 are pressurized independently, the motor 86 willretract slowly. If pipes 90, 97 are pressurized concurrently, motor 86will retract rapidly.

An important feature of the invention resides in the internal ducting,yas abovedescribed, within the Walls or bodies of the various cylindersand pistons, thus to protect these ducts from injury or damage.Accordingly, hydraulic hoses which might otherwise be exposed tobreakage and injury are eliminated.

FIG. 18 illustrates one of the two hydraulic motors 81, 82 incorporatedin the respective chain cases 57, 58, as shown in FIG. 5. Motor 81 isillustrated. It is connected at one end to a link of the chain 61, andat its other end to an end wall 173 of the chain case.

Means are provided producing selected multiple force motor action. Forthis purpose, motor 81 comprises a base cylinder 174 having therewithina piston 175 which carriesone end of a sleeve 176 which functions as apiston rod, which slides in bearing at the other end of cylinder 174.The exposed end of rod 176 carries yan end head 177 which is coupled tothe chain 61 on pin 178. Fixed within the motor 81 is a hydraulic iluidtube 181 which carries at its end a xed position piston 182 which iswithin the chamber 183 of sleeve 176. One stage of hydraulic uid isadmitted to the motor through the tube 181 and is ported into a chamber184 at one side of the fixed pis- -ton 182 through end ducts 185, thusto exert pressure on movable piston and pull the chain to the left, asshown in FIG. 18.

Additional pressure can be supplied through pipe 186 to chamber 187between cylinders 174, 176, thus to exert further pressure on the piston175 to move it to the left. Controls are provided to pressurize chambers187 and 184 independently or concurrently to vary the total forceexerted by the motor 81 on the chain 61.

The respective motors 81, 82 are single acting and have a Working strokein one direction only to pull on the chain 61. When one motor pulls theother is de-actuated, and it is pulled along with the chain.Accordingly, the chain will travel in the direction in which it ispulled by one or the other of the motors 81, 82, thus to turn post 79and swing the bucket 62.

The ends of the several internal ducts 157, 158, 159, 163, 164 in FIG.16 are closed by threaded plugs 190, the ends of which are desirably ushwith the outer wall of the part to which they are attached.

What is claimed is:

1. A tunneling machine comprising:

a tunneling shield disposed on a substantially horizontal axis andhaving a roof for supporting earth over an excavated part of the tunnel,

excavator support mechanism on said shield and conveyed by said shieldas the shield moves forward in the tunnel,

a power operated excavator mounted on said support mechanism to becarried Within the shield and conveyed by the shield,

said excavator comprising a frame, a bottom extending forwardly of theframe, a cutting tool on the boom to remove spoil from the tunnel face,and

means for moving the cutting tool in all directions across the tunnelface.

2. The tunneling machine of claim 1 in which the tool comprises abucket, said support mechanism comprising a track longitudinal of theshield and on which the excavator is retractable from the tunnel face todeposit a bucket load on take out apparatus spaced rearwardly from thetunnel face.

3. The tunneling machine of claim 1 in which the excavator framecomprises a central rotor on which the boom is mounted and a bearing onwhich the rotor turns on an axis longitudinal of the tunnel.

4. The machine of claim 1 in which the excavator frame comprises a rigidtube, Outrigger arms supporting said tube from said support mechanismsubstantially at the center of the shield, a rotor journaled on saidtube, a motor to turn the rotor, and a coupling between the rotor andthe boom.

5. The machine of claim 1 in which said support mechanism comprises atrack longitudinal of the shield, said frame having wheeled supportmeans movable along said track, and a motor reacting between the shieldand frame for advancing and retracting said frame on said track withrespect to the tunnel face.

6. The tunneling machine of claim 1 in combination with ya hydraulicallypowered motor to swing the boom, a pump for hydraulic uid and ahydraulic line from the pump to the motor, said motor comprising acylinder having a wall, said line comprising a duct within said wallwhereby the wall shields the line duct from injury.

7. The machine of claim 1 in which the said support mechanism comprisestracks mounted on the sides of the shield, the excavator being disposedsubstantially at the center of the shield in the space between saidtracks and having laterally projecting outrigger arms with wheeledcarriages movable along said tracks.

8. The machine of claim 7 in which said wheels are provided with meansfor pressing them against their respective tracks.

9. A tunneling machine excavator comprising:

a tube,

a support to hold the tube on a substantially horizontal taxis,

a rotor journaled in the tube for rotation on said substantiallyhorizontal axis,

motor means to turn the rotor,

a boom pivotally connected to the rotor,

a cutting tool pivotally connected to the end of the boom,

a motor for pivotally lmoving the boom about its connection to therotor,

and ya motor for pivotally moving the tool about its connection to theboom.

10. The excavator of claim 9 in which the support for the tube compriseslaterally extending Outrigger arms, carriages at the ends of said arms,wheels on the carriages and motors to project the wheels fromthecarriages for pressure contact with a track.

l11. The excavator of claim 9 in which the support for the tubecomprises front and rear sets of paired, laterally extending Outriggerarms, and front and rear journals for said rotor respectively proximatesaid sets of arms to receive loading support therefrom.

12. The excavator of claim 8 in combination with a tunneling shield,tracks spaced at the sides 0f the shield, the support for the tubecomprising laterally projecting Outrigger ar-ms to support the tube inthe space between said tracks, said arms having end carriages carried onsaid tracks and a motor for moving said excavator along said tracks.

13. The combination of claim 12 in which the tracks comprise inwardlyfacing channels in which the carriages fit. l

14. The combination of claim 12 in which said motor comprises a jackbetween said track and said excavator.

15. A tunneling machine excavator comprising a tube, a support for thetube, a rotor journaled in the tube, motor means to turn the rotor, aboom pivotally connected to the rotor, a cutting tool pivotallyconnected to the end yof the boom, a motor for pivotally moving the boomabout its connection to the rotor, and a motor for pivotally moving thetool about its connection to the boom, a sleeve coaxially within thetube, another tube coaxial with said tube and sleeve and spaced radiallyinwardly with respect to said sleeve to leave an lannular spacetherebetween, said motor means comprising a plurality of motorsdistributed annularly in said space about said other tube.

16. A tunneling machine comprising a shield, an excavator in the shield,said excavator having a boom and a cutting tool at the end of the boom,a hydraulically powered motor to swing the boom, said motor comprising aram having multiple telescopically retractable sections and a multipleof fluid chambers corresponding to the number of telescopicallyretractable sections and means for independently or concurrentlypressurizing said chambers for selected multiple speed ram action.

17. A tunneling machine comprising a shield, an excavator in the shield,Said excavator having a boom, a cutting tool at the end of the boom, andhydraulically powered motor means to swing the cutting tool at the endof the boom, said motor means having multiple telescopically relatedsections and a multiple of uid chambers corresponding to the number oftelescopically Irelated sections and means for independently orconcurrently pressurizing said chambers Ifor selected multiple forcemotor action.

18. The tunneling machine of claim 17 in which the cutting tool ismounted on the boom on a pintle, a chain about said pintle, said motormeans comprising two hydraulic motors, one at each end of the chain,each said motor having multiple telescopically -related sections andmultiple fluid chambers.

References Cited UNITED STATES PATENTS 1,987,982 1/1935 Wheeler 299-562,111,405 3/1938A Parker 61-84 2,587,844 3/1952 Harrison 214-1332,593,693 4/1952 Osgood.

3,042,234 7/1962 Davis 214-141 ERNEST R. PURSER, Primary Examiner.'

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, D C. 20231 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,404,920October 8, 1968 John R. Tabor It is certified that error appears in theabove identified patent and that said Letters Patent are herebycorrected as shown below:

Column 7, line 18, "bottom" should read boom Signed and sealed this 3rdday of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Ir.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR.

